You can make an animated GIF from a video on your screen. (You can also draw your own animations.)
Remove the stylus and tap 
Or, open quick settings and tap GIF maker.
Adjust the GIF's frame over the video:


To start recording tap 
You can capture up to 15 seconds. To stop recording before that, tap 
To view immediately, touch the 
To view any time, open the Photos, Files, or other media viewing app, and look for the Screenshots folder.